Conventionally, liquid crystal display devices using nematic liquid crystals are mainly utilized as the display device for mobile terminals such as cellular phones, because of their low driving voltage as well as low power consumption characteristics, and their production increases with recent rapid propagation of mobile terminals.
At the same time, higher display functions such as the increase of the number of pixels as well as the number of characters has been required.
On the other hand, it is also important to comply not only with the requirement for advanced display functions such as higher resolution, but also with the requirement for low power consumption, because there is a strong requirement to maintain or extend the continuous operation time for the battery of mobile apparatus.
As one of technologies to fulfill such requirements, several methods intended to develop so-called display memory characteristics are proposed for liquid crystal display device wherein contents of the display is maintained even in the case that the power is shut off. Using the memory characteristics, it is possible to reduce the power consumption substantially to zero in principle when the contents of the display are not changed, and it is also possible to reduce the power consumption by changing the contents of the display on pixel basis by applying voltage only on pixels in which the contents of the display is changed.
Furthermore, as has been well known in the case of conventional passive matrix driving system by twisted nematic (TN) or super twisted nematic (STN) mode, the upper limit of the number of pixels is determined by the limitation of a duty ratio. The use of the memory characteristics removes the limit of the number of pixels and enables a display with high resolution.
As related arts realizing the display memory characteristics using nematic liquid crystals, for example, a method combining a nematic liquid crystal and a liquid crystal alignment layer subjected to a fine grating fabrication process (see patent document 1), and a method by the present inventors in which a nematic liquid crystal and domains having a plurality of in-plane liquid crystal anchoring directions on a substrate are arranged in a patterned form (see patent document 2), are proposed.
Patent document 1: Japanese Unexamined Patent Application Publication No. 11-513809.
Patent document 2: WO 02/06887.